问题
The HTML5 spec mentions an UndoManager that can be used to query the previous state of a document that's been edited by a user ( http://www.whatwg.org/specs/web-apps/current-work/#undomanager ). Do any browsers support this? Is there any hope of browsers ever supporting it?
回答1:
You can test your own browsers by navigating them to HTML5Test.com. You can also test for it on your page (and then use it if it exists) by doing the following:
return typeof UndoManager !== 'undefined';
The browsers that currently support it are limited.
No Support: Chrome 6.0, IE 8, FF 3.6
Browser Score (160) UndoManager Support
--------------------------------------
IE8 19 no
FF3.6 101 no
Chrome 6 142 no
Safari 4.0.5 70 no
Opera 10.53 102 no
Chrome, Firefox, and Opera score well on overall HTML5 support. So, UndoManager support may be coming soon. Safari has promised full HTML5 support "soon", as well. IE9 is supposed to be more focused on web standards.
So, it doesn't look right at this moment, but I imagine there will be 3-4 major browsers with support in the near future.
来源：https://stackoverflow.com/questions/2858919/javascript-undomanager-browser-support